1. Field of the Invention
The present invention relates to a process for treating organic phosphoric acid compounds generated as a waste organic solvent in a uranium refining process or in a reprocessing of nuclear fuel.
2. Description of Prior Art
Organic phosphoric acid compounds such as tributyl phosphate or the like used for extracting uranium or plutonium in refining uranium or reprocessing spent nuclear fuels are mostly stored in the form of liquid as a waste after repeated use for several times. This is mainly because the waste solvent contains radioactive substances or because the organic phosphate solvent contains phosphor on which standard for release is set up and therefore it cannot be released as it is or phosphor produced after burning cannot be released to the atmosphere. However, it is undesirable to store the organic phosphate solvent in the form of liquid because there is a possibility of leakage and the solvent has a poor chemical stability. In order to overcome the disadvantages, some processing methods have been tried. For example, Japanese Patent Publication (Kokai) No. Sho 63-67595 describes a process of solidifying organic phosphates by adding thereto a solidifying agent such as hydrated aluminum chloride or polyaluminum chloride. This process has a problem that the solidifying agent is a chloride and therefore chlorine gas, hydrogen chloride or chlorides are released to the atmosphere in heating step in which solidified products are obtained. The processes disclosed in Japanese Patent Publications Nos. Sho 63-262597 and Sho 63-290998 are processes in which organic phosphoric acids are oxidatively decomposed under wet heat conditions and then solidified by the addition of alkaline earth metal hydroxides. These processes have a problem that wet heat conditions involve high pressures rather than normal pressure, which leads to specialization of apparatus to be used.